Lubricant compositions

ABSTRACT

The lubricant compositions of the present disclosure comprises a base oil and an additive composition comprising, for example, a detergent and an additive chosen from a phosphorus-containing compound, a friction modifier, and a dispersant, wherein the additive composition exhibits at least one of reduced thin-film friction and increased fuel efficiency as compared to an additive composition that is devoid of the detergent and the additive. As a further example, the additive composition can comprise a friction modifier and a dispersant, wherein the additive composition exhibits at least one of reduced thin-film friction and increased fuel efficiency as compared to an additive composition that is devoid of the friction modifier and the dispersant. Methods of using the additive and lubricant compositions are also disclosed.

DESCRIPTION OF THE DISCLOSURE

1. Field of the Disclosure

The present disclosure relates to lubricant compositions comprising a base oil and an additive composition comprising, for example, a detergent and an additive chosen from a phosphorus-containing compound, a friction modifier, and a dispersant, and as a further example a friction modifier and a dispersant. Methods of using the additive and lubricant compositions are also disclosed.

2. Background of the Disclosure

In recent years there has been a growing desire to produce energy-efficient lubricated components. Moreover, modern engine oil specifications require lubricants to demonstrate fuel efficiency in standardized engine tests. The thickness and frictional characteristics of thin lubricant films are known to affect the fuel efficiency properties of, for example, crankcase oils and gear oils. Improved fuel efficiency is achieved when thin-film friction is reduced. Thin-film friction is the friction generated from fluid, such as a lubricant, pushing between two surfaces, wherein the distance between the two surfaces is very narrow. It is known that different additives normally present in a lubricant composition form films of different thicknesses, which can have an effect on thin-film friction. Some additives, such as zinc dialkyl dithiophosphate (ZDDP) are known to increase thin-film friction, when added to a base oil. These additives are required to be present in lubricants in order to protect engines and gears, however, the increase in thin-film friction can be detrimental to fuel efficiency.

Moreover, it is also known that some additives are very expensive. And, the use of additional amounts of an additive to a lubricant composition to reduce thin-film friction can be quite costly to the manufacturer.

What is needed is a lubricant composition that is inexpensive and can provide at least one of reduced thin-film friction and increased fuel economy.

SUMMARY OF THE DISCLOSURE

In accordance with the disclosure, there is disclosed an additive composition comprising a detergent and an additive chosen from a phosphorus-containing compound, a friction modifier, and a dispersant, wherein the additive composition exhibits at least one of reduced thin-film friction and increased fuel efficiency as compared to an additive composition that is devoid of the detergent and the additive.

According to another aspect, there is disclosed an additive composition comprising a friction modifier and a dispersant, wherein the additive composition exhibits at least one of reduced thin-film friction and increased fuel efficiency as compared to an additive composition that is devoid of the friction modifier and the dispersant.

According to yet another aspect, there is disclosed a method of reducing thin-film friction of a fluid between surfaces comprising providing to the fluid a lubricant composition comprising a base oil and an additive composition comprising a detergent and an additive chosen from a phosphorus-containing compound, a friction modifier, and a dispersant.

Moreover, there is disclosed a method of reducing thin-film friction of a fluid between surfaces comprising providing to the fluid a lubricant composition comprising a base oil and an additive composition comprising a friction modifier and a dispersant.

There is further disclosed a method of increasing fuel efficiency in a vehicle comprising providing to a vehicle a composition comprising a base oil and an additive composition comprising a detergent and an additive chosen from a phosphorus-containing compound, a friction modifier, and a dispersant.

In various aspects, there is disclosed a method of increasing fuel efficiency in a vehicle comprising providing to a vehicle a composition comprising a base oil and an additive composition comprising a friction modifier and a dispersant.

Additional advantages of the embodiments will be set forth in part in the description which follows, and can be learned by practice of the disclosure. The advantages will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure, as claimed.

DESCRIPTION OF THE EMBODIMENTS

The present disclosure relates to lubricant compositions comprising a major amount of a base oil and a minor amount of an additive composition comprising a detergent and an additive chosen from a phosphorus-containing compound, a friction modifier, and a dispersant, wherein the additive composition exhibits at least one of reduced thin-film friction and increased fuel efficiency as compared to an additive composition that is devoid of the detergent and the additive. In an aspect, the additive composition can comprise a friction modifier and a dispersant.

The base oil can be present in the lubricating composition in any desired or effective amount. For example, the base oil can be present in a major amount. A “major amount” is understood to mean greater than or equal to 50% by weight relative to the total weight of the composition. As a further example, the base oil can be present in an amount greater than or equal to 80%, and as an additional example, greater than or equal to 90% by weight relative to the total weight of the composition.

Base oils suitable for use in formulating the disclosed lubricant compositions can be selected from any of the synthetic or mineral oils or mixtures thereof. Mineral oils include animal oils and vegetable oils (e.g., castor oil, lard oil) as well as other mineral lubricating oils such as liquid petroleum oils and solvent treated or acid-treated mineral lubricating oils of the paraffinic, naphthenic or mixed paraffinic-naphthenic types. Oils derived from coal or shale can also suitable. Further, oils derived from a gasto-liquid process can also be suitable.

Non-limiting examples of synthetic oils include hydrocarbon oils such as polymerized and interpolymerized olefins (e.g., polybutylenes, polypropylenes, propylene isobutylene copolymers, etc.); polyalphaolefins (e.g. poly(1-hexenes), poly-(1-octenes), poly(1-decenes), etc., and mixtures thereof); alkylbenzenes (e.g., dodecylbenzenes, tetradecylbenzenes, di-nonylbenzenes, di-(2-ethylhexyl)benzenes, etc.); polyphenyls (e.g., biphenyls, terphenyl, alkylated polyphenyls, etc.); alkylated diphenyl ethers and alkylated diphenyl sulfides and the derivatives, analogs and homologs thereof and the like.

Hence, the base oil which can be used to make the compositions as described herein can be selected from any of the base oils in Groups I-IV as specified in the American Petroleum Institute (API) Base Oil Interchangeability Guidelines. Such base oil groups are as follows:

Group I contain less than 90% saturates and/or greater than 0.03% sulfur and have a viscosity index greater than or equal to 80 and less than 120; Group II contain greater than or equal to 90% saturates and less than or equal to 0.03% sulfur and have a viscosity index greater than or equal to 80 and less than 120; Group III contain greater than or equal to 90% saturates and less than or equal to 0.03% sulfur and have a viscosity index greater than or equal to 120; and Group IV are polyalphaolefins (PAO).

The test methods used in defining the above groups are ASTM D2007 for saturates; ASTM D2270 for viscosity index; and one of ASTM D2622, 4294, 4927 and 3120 for sulfur.

Group IV basestocks, i.e. polyalphaolefins (PAO) include hydrogenated oligomers of an alpha-olefin, the most important methods of oligomerisation being free radical processes, Ziegler catalysis, and cationic, Friedel-Crafts catalysis.

The polyalphaolefins typically have viscosities in the range of about 2 to about 100 cSt at 100° C., for example about 4 to about 8 cSt at 100° C. They can, for example, be oligomers of branched or straight chain alpha-olefins having from about 2 to about 30 carbon atoms, non-limiting examples include polypropenes, polyisobutenes, poly-1-butenes, poly-1-hexenes, poly-1-octenes and poly-1-decene. Included are homopolymers, interpolymers and mixtures.

Basestocks suitable for use herein can be made using a variety of different processes including but not limited to distillation, solvent refining, hydrogen processing, oligomerisation, and re-refining.

The base oil can be an oil derived from. Fischer-Tropsch synthesized hydrocarbons. Fischer-Tropsch synthesized hydrocarbons can be made from synthesis gas containing H₂ and CO using a Fischer-Tropsch catalyst. Such hydrocarbons typically require further processing in order to be useful as the base oil. For example, the hydrocarbons can be hydroisomerized using processes disclosed in U.S. Pat. Nos. 6,103,099 or 6,180,575; hydrocracked and hydroisomerized using processes disclosed in U.S. Pat. Nos. 4,943,672 or 6,096,940; dewaxed using processes disclosed in U.S. Pat. No. 5,882,505; or hydroisomerized and dewaxed using processes disclosed in U.S. Pat. Nos. 6,013,171; 6,080,301; or 6,165,949.

Unrefined, refined and rerefined oils, either mineral or synthetic (as well as mixtures of two or more of any of these) of the type disclosed hereinabove can be used in the base oils. Unrefined oils are those obtained directly from a mineral or synthetic source without further purification treatment. For example, a shale oil obtained directly from retorting operations, a petroleum oil obtained directly from primary distillation or ester oil obtained directly from an esterification process and used without further treatment would be an unrefined oil. Refined oils are similar to the unrefined oils except they have been further treated in one or more purification steps to improve one or more properties. Many such purification techniques are known to those skilled in the art such as solvent extraction, secondary distillation, acid or base extraction, filtration, percolation, etc. Rerefined oils are obtained by processes similar to those used to obtain refined oils applied to refined oils which have been already used in service. Such rerefined oils are also known as reclaimed or reprocessed oils and often are additionally processed by techniques directed to removal of spent additives, contaminants, and oil breakdown products.

Certain of these types of base oils may be used for the specific properties they possess such as biodegradability, high temperature stability, or non-flammability. In other compositions, other types of base oils may be preferred for reasons of availability or lower cost. Thus, the skilled artisan will recognize that while various types of base oils discussed above may be used in the lubricant compositions of this invention, they are not necessarily equivalents of each other in every application.

In an aspect, the detergent for use in the disclosed additive composition can be a metallic detergent. A suitable metallic detergent can include an oil-soluble neutral or overbased salt of alkali or alkaline earth metal with one or more of the following acidic substances (or mixtures thereof): (1) a sulfonic acid, (2) a carboxylic acid, (3) a salicylic acid, (4) an alkyl phenol, (5) a sulfurized alkyl phenol, and (6) an organic phosphorus acid characterized by at least one direct carbon-to-phosphorus linkage. Such an organic phosphorus acid can include those prepared by the treatment of an olefin polymer (e.g., polyisobutylene having a molecular weight of about 1,000) with a phosphorizing agent such as phosphorus trichloride, phosphorus heptasulfide, phosphorus pentasulfide, phosphorus trichloride and sulfur, white phosphorus and a sulfur halide, or phosphorothioic chloride.

The term “overbased” in connection with metallic detergents is used to designate metal salts wherein the metal is present in stoichiometrically larger amounts than the organic radical. The commonly employed methods for preparing the overbased salts involve heating a mineral oil solution of an acid with a stoichiometric excess of a metal neutralizing agent such as the metal oxide, hydroxide, carbonate, bicarbonate, or sulfide at a temperature of about 50° C., and filtering the resultant product. The use of a “promoter” in the neutralization step to aid the incorporation of a large excess of metal likewise is known. Examples of compounds useful as the promoter include phenolic substances such as phenol, naphthol, alkyl phenol, thiophenol, sulfurized alkylphenol, and condensation products of formaldehyde with a phenolic substance; alcohols such as methanol, 2-propanol, octanol, 2-ethoxyethanol, diethylene glycol ethyl ether, ethylene glycol, stearyl alcohol, and cyclohexyl alcohol; and amines such as aniline, phenylene diamine, phenothiazine, phenyl-beta-naphthylamine, and dodecylamine. A particularly effective method for preparing the basic salts comprises mixing an acid with an excess of a basic alkaline earth metal neutralizing agent and at least one alcohol promoter, and carbonating the mixture at an elevated temperature such as 60° C. to 200° C.

Examples of suitable metal-containing detergents include, but are not limited to, neutral and overbased salts of such substances as neutral sodium sulfonate, an overbased sodium sulfonate, a sodium carboxylate, a sodium salicylate, a sodium phenate, a sulfurized sodium phenate, a lithium sulfonate, a lithium carboxylate, a lithium salicylate, a lithium phenate, a sulfurized lithium phenate, a calcium sulfonate, a calcium carboxylate, a calcium salicylate, a calcium phenate, a sulfurized calcium phenate, a magnesium sulfonate, a magnesium carboxylate, a magnesium salicylate, a magnesium phenate, a sulfurized magnesium phenate, a potassium sulfonate, a potassium carboxylate, a potassium salicylate, a potassium phenate, a sulfurized potassium phenate, a zinc sulfonate, a zinc carboxylate, a zinc salicylate, a zinc phenate, and a sulfurized zinc phenate. Further examples include a calcium, lithium, sodium, potassium, and magnesium salt of a hydrolyzed phosphosulfurized olefin having about 10 to about 2,000 carbon atoms or of a hydrolyzed phosphosulfurized alcohol and/or an aliphatic-substituted phenolic compound having about 10 to about 2,000 carbon atoms. Even further examples include a calcium, lithium, sodium, potassium, and magnesium salt of an aliphatic carboxylic acid and an aliphatic substituted cycloaliphatic carboxylic acid and many other similar alkali and alkaline earth metal salts of oil-soluble organic acids. A mixture of a neutral or an overbased salt of two or more different alkali and/or alkaline earth metals can be used. Likewise, a neutral and/or an overbased salt of mixtures of two or more different acids can also be used.

As is well known, overbased metal detergents are generally regarded as containing overbasing quantities of inorganic bases, generally in the form of micro dispersions or colloidal suspensions. Thus the term “oil-soluble” as applied to metallic detergents is intended to include metal detergents wherein inorganic bases are present that are not necessarily completely or truly oil-soluble in the strict sense of the term, inasmuch as such detergents when mixed into base oils behave much the same way as if they were fully and totally dissolved in the oil. Collectively, the various metallic detergents referred to herein above, are sometimes called neutral, basic, or overbased alkali metal or alkaline earth metal-containing organic acid salts.

Methods for the production of oil-soluble neutral and overbased metallic detergents and alkaline earth metal-containing detergents are well known to those skilled in the art, and extensively reported in the patent literature. See, for example, U.S. Pat. Nos. 2,001,108; 2,081,075; 2,095,538; 2,144,078; 2,163,622; 2,270,183; 2,292,205; 2,335,017; 2,399,877; 2,416,281; 2,451,345; 2,451,346; 2,485,861; 2,501,731; 2,501,732; 2,585,520; 2,671,758; 2,616,904; 2,616,905; 2,616,906; 2,616,911; 2,616,924; 2,616,925; 2,617,049; 2,695,910; 3,178,368; 3,367,867; 3,496,105; 3,629,109; 3,865,737; 3,907,691; 4,100,085; 4,129,589; 4,137,184; 4,184,740; 4,212,752; 4,617,135; 4,647,387; and 4,880,550.

The metallic detergents utilized in this invention can, if desired, be oil-soluble boronated neutral and/or overbased alkali of alkaline earth metal-containing detergents. Methods for preparing boronated metallic detergents are described in, for example, U.S. Pat. Nos. 3,480,548; 3,679,584; 3,829,381; 3,909,691; 4,965,003; and 4,965,004.

The detergent can be present in the lubricant composition in any desired or effective amount. In an aspect, the lubricant composition can comprise from about 0.01% to about 0.8% by weight, for example from about 0.05% to about 0.6%, and as a further example from about 0.09% to about 0.4% by weight relative to the total weight of the lubricating composition. In an aspect, the additive composition can comprise from about 0.06% to about 5% by weight, for example from about 0.30% to about 3.6%, and as a further example from about 0.54% to about 2.38% by weight relative to the total weight of the additive composition. However, one of ordinary skill in the art would understand that any amount can be used.

The disclosed additive composition can comprise a phosphorus-containing compound. In an aspect, the phosphorus-containing compound can be a metal containing, phosphorus-containing compound. For example, the metal containing, phosphorus-containing compound can be a dihydrocarbyl dithiophosphate metal salt. The metal in the dihydrocarbyl dithiophosphate metal can be an alkali or alkaline earth metal, or aluminium, lead, tin, molybdenum, manganese, nickel or copper. Zinc salts can be used, for example, zinc dialkyl dithiophosphate.

The metal dihydrocarbyl dithiophosphate salts can be prepared in accordance with known techniques by first forming a dihydrocarbyl dithiophosphoric acid (DDPA), usually by reaction of one or more alcohol or a phenol with P₂S₅ and then neutralizing the formed DDPA with a zinc compound. For example, a dithiophosphoric acid can be made by reacting mixtures of primary and secondary alcohols. Alternatively, multiple dithiophosphoric acids can be prepared comprising both hydrocarbyl groups that are entirely secondary in character and hydrocarbyl groups that are entirely primary in character. To make the zinc salt, any basic or neutral zinc compound can be used but the oxides, hydroxides, and carbonates are most generally employed.

The zinc dihydrocarbyl dithiophosphates can be oil-soluble salts of dihydrocarbyl dithiophosphoric acids and can be represented by the following formula: [(RO)(R¹O)P(S)]₂Z_(n) where R and R¹ can be the same or different hydrocarbyl radicals containing from about 1 to about 18, for example from about 2 to about 12, carbon atoms and including radicals such as alkyl, alkenyl, aryl, arylalkyl, alkaryl and cycloaliphatic radicals. In an aspect, R and R¹ groups can be alkyl groups of about 2 to about 8 carbon atoms. Thus, the radicals can, for example, be ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, amyl, n-hexyl, i-hexyl, n-octyl, decyl, dodecyl, octadecyl, 2-ethylehexyl, phenyl, butylphenyl, cyclohexyl, methylcyclopentyl, propenyl, and butenyl. In order to obtain oil-solubility, the total number of carbon atoms (i.e. in R and R¹ in the dithiophosphoric acid can generally be 5 or greater. The zinc dihydrocarbyl dithiophosphate can therefore comprise zinc dialkyl dithiophosphates.

Moreover, the phosphorus-containing compound can include oil-soluble amine salts of a phosphoric acid ester, such as those taught in U.S. Pat. Nos. 5,354,484 and 5,763,372, the disclosures of which are hereby incorporated by reference; and reaction products of dicyclopentadiene and a thiophosphoric acid.

The amine salts of a phosphoric acid ester can be prepared by reacting a phosphoric acid ester with ammonia or a basic nitrogen compound, such as an amine. The salts can be formed separately, and then the salt of the phosphoric acid ester can be added to the additive composition.

The phosphoric acid esters useful in preparing the amine salts of the present invention can be characterized by the formula

wherein R¹ can be hydrogen or a hydrocarbyl group, R² can be a hydrocarbyl group, and both X groups can be either O or S.

An exemplary method of preparing compositions containing (I) comprises reacting at least one hydroxy compound of the formula ROH with a phosphorus compound of the formula P₂X₅ wherein R can be a hydrocarbyl group and X can be O or S. The phosphorus-containing compounds obtained in this manner can be mixtures of phosphorus compounds, and are generally mixtures of mono- and dihydrocarbyl-substituted phosphoric and/or dithiophosphoric acids depending on a choice of phosphorus reactant (i.e., P₂O₅ or P₂S₅).

The hydroxy compound used in the preparation of the phosphoric acid esters of this disclosure can be characterized by the formula ROH wherein R can be hydrocarbyl group. The hydroxy compound reacted with the phosphorus compound can comprise a mixture of hydroxy compounds of the formula ROH wherein the hydrocarbyl group R can contain from about 1 to about 30 carbon atoms. It is necessary, however, that the amine salt of the substituted phosphoric acid ester ultimately prepared is soluble in the lubricating compositions of the present disclosure. Generally, the R group will contain at least about 2 carbon atoms, typically about 3 to about 30 carbon atoms.

The R group can be aliphatic or aromatic such as alkyl, aryl, alkaryl, aralkyl and alicyclic hydrocarbon groups. Non-limiting examples of useful hydroxy compounds of the formula ROH include, for example, ethyl alcohol, iso-propyl, n-butyl alcohol, amyl alcohol, hexyl alcohol, 2-ethyl-hexyl alcohol, nonyl alcohol, dodecyl alcohol, stearyl alcohol, amyl phenol, octyl phenol, nonyl phenol, methyl cyclohexanol, and alkylated naphthol, etc.

In an aspect the alcohols, ROH, can be aliphatic alcohols and for example, primary aliphatic alcohols containing at least about 4 carbon atoms. Accordingly, examples of the exemplary monohydric alcohols ROH which can be useful in the present disclosure include, amyl alcohol, 1-octanol, 1-decanol, 1-dodecanol, 1-tetradecanol, 1-hexadecanol, 1-octadecanol, oleyl alcohol, linoleyl alcohol, linolenyl alcohol, phytol, myricyl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol and behenyl alcohol. Commercial alcohols (including mixtures) are contemplated herein, and these commercial alcohols can comprise minor amounts of alcohols which, although not specified herein, do not detract from the major purposes of this disclosure.

The molar ratio of the hydroxy compound ROH to phosphorus reactant P₂X₅ in the reaction should be within the range of from about 1:1 to about 4:1, an exemplary ratio being 3:1. The reaction can be effected simply by mixing the two reactants at an elevated temperature such as temperatures above about 50° C. up to the composition temperature of any of the reactants or the desired product. In an aspect, the temperature can range from about 50° C. to about 150° C., and can be most often below about 100° C. The reaction can be carried out in the presence of a solvent which facilitates temperature control and mixing of the reactants. The solvent can be any inert fluid substance in which either one or both reactants are soluble, or the product is soluble. Such solvents include benzene, toluene, xylene, n-hexane, cyclohexane, naphtha, diethyl ether carbitol, dibutyl ether dioxane, chlorobenzene, nitrobenzene, carbon tetrachloride or chloroform.

The product of the above reaction is acidic, but its chemical constitution is not precisely known. Evidence indicates, however, that the product is a mixture of acidic phosphates comprising predominantly of the mono- and di-esters of phosphoric acid (or thio- or dithiophosphoric acid), the ester group being derived from the alcohol ROH.

The amine salts of the present disclosure can be prepared by reaction of the above-described phosphoric acid esters such as represented by Formula I with at least one amino compound which can be a primary or secondary. In an aspect, the amines which are reacted with the substituted phosphoric acids to form the amine salts are primary hydrocarbyl amines having the general formula

R′NH₂

wherein R′ can be a hydrocarbyl group containing up to about 150 carbon atoms and will more often be an aliphatic hydrocarbyl group containing from about 4 to about 30 carbon atoms.

In an aspect, the hydrocarbyl amines which are useful in preparing the amine salts of the present disclosure can be primary hydrocarbyl amines containing from about 4 to about 30 carbon atoms in the hydrocarbyl group, and for example from about 8 to about 20 carbon atoms in the hydrocarbyl group. The hydrocarbyl group can be saturated or unsaturated. Representative examples of primary saturated amines are those known as aliphatic primary fatty amines. Typical fatty amines include alkyl amines such as n-hexylamine, n-octylamine, n-decylamine, n-dodecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-octadecylamine (stearyl amine), etc. These primary amines are available in both distilled and technical grades. While the distilled grade will provide a purer reaction product, the desirable amides and imides will form in reactions with the amines of technical grade. Also suitable are mixed fatty amines.

In another aspect, the amine salts of the phosphorus-containing compound can be those derived from tertiary-aliphatic primary amines having at least about 4 carbon atoms in the alkyl group. For the most part, they can be derived from alkyl amines having a total of less than about 30 carbon atoms in the alkyl group. Usually the tertiary aliphatic primary amines are monoamines represented by the formula

R(CH₃)₂CNH₂

wherein R can be a hydrocarbyl group containing from one to about 30 carbon atoms. Such amines can be illustrated by tertiary-butyl amine, tertiary-hexyl primary amine, 1-methyl-1-amino-cyclohexane, tertiary-octyl primary amine, tertiary-decyl primary amine, tertiary-dodecyl primary amine, tertiary-tetradecyl primary amine, tertiary-hexadecyl primary amine, tertiary-octadecyl primary amine, tertiary-tetracosanyl primary amine, tertiary-octacosanyl primary amine.

Mixtures of amines are also useful for the purposes of this disclosure. Illustrative of amine mixtures of this type is a mixture of C₁₁-C₁₄ tertiary alkyl primary amines and a similar mixture of C₁₈-C₂₂ tertiary alkyl primary amines. The tertiary alkyl primary amines and methods for their preparation are well known to those of ordinary skill in the art and, therefore, further discussion is unnecessary. The tertiary alkyl primary amine useful for the purposes of this disclosure and methods for their preparation are described in U.S. Pat. No. 2,945,749, which is hereby incorporated by reference for its teaching in this regard.

Primary amines in which the hydrocarbon chain comprises olefinic unsaturation also are quite useful. Thus, the R′ and R″ groups may contain one or more olefinic unsaturation depending on the length of the chain, usually no more than one double bond per 10 carbon atoms. Representative amines are dodecenylamine, myristoleylamine, palmitoleylamine, oleylamine and linoleylamine.

Secondary amines include dialkylamines having two of the above alkyl groups including such commercial fatty secondary amines, and also mixed dialkylamines where R′ is a fatty amine and R″ may be a lower alkyl group (1-9 carbon atoms) such as methyl, ethyl, n-propyl, i-propyl, butyl, etc., or R″ may be an alkyl group bearing other non-reactive or polar substituents (CN, alkyl, carbalkoxy, amide, ether, thioether, halo, sulfoxide, sulfone) such that the essentially hydrocarbon character of the radical is not destroyed. The fatty polyamine diamines include mono-or dialkyl, symmetrical or asymmetrical ethylene diamines, propane diamines (1,2, or 1,3), and polyamine analogs of the above. Suitable polyamines include N-coco-1,3-diaminopropane,N-soyaalkyl trimethylenediamine, N-tallow-1,3-diaminopropane, or N-oleyl-1,3-diaminopropane.

The oil-soluble amine salts can be prepared by mixing the above-described phosphoric acid esters with the above-described amines at room temperature or above. Generally, mixing at room temperature for a period of from up to about one hour is sufficient. The amount of amine reacted with the phosphoric acid ester to form the salts of the disclosure is at least about one equivalent weight of the amine (based on nitrogen) per equivalent of phosphoric acid, and the ratio of equivalents generally is about one.

Methods for the preparation of such amine salts are well known and reported in the literature. See for example, U.S. Pat. Nos. 2,063,629; 2,224,695; 2,447,288; 2,616,905; 3,984,448; 4,431,552; 5,354,484; Pesin et al, Zhurnal Obshchei Khimii, Vol, 31, No. 8, pp. 2508-2515 (1961); and PCT International Application Publication No. WO 87/07638, the disclosures of all of which are hereby incorporated by reference.

Alternatively, the salts can be formed in situ when the acidic phosphoric acid ester is blended with the above-described amines when forming a gear oil concentrate or the formulated gear oil itself.

Another phosphorus-containing compound for use in the lubricating composition herein comprises the reaction products of dicyclopentadiene and thiophosphoric acids, also referred to herein as dicyclopentadiene dithioates. thiophosphoric acids have the formula:

wherein R can be a hydrocarbyl group having from about 2 to about 30, for example from about 3 to about 18 carbon atoms. In an aspect, R comprises a mixture of hydrocarbyl groups containing from about 3 to about 18 carbon atoms.

In an aspect, the phosphorus-containing compound is at least one of neopentyl glycol phosphite, a sulfur-containing, neopentyl glycol phospite, and a salt of a sulfur-containing, neopentyl glycol phosphite.

The dicyclopentadiene dithioates can be prepared by mixing dicyclopentadiene and a dithiophosphoric acid for a time and temperature sufficient to react the thioacid with the dicylcopentadiene, Typical reaction times can range from 30 minutes to 6 hours, although suitable reaction conditions can readily be determined by one skilled in the art. The reaction product can be subjected to conventional post-reaction work up including vacuum stripping and filtering.

The phosphorus-containing compound can be present in the lubricant composition in any desired or effective amount. In an aspect, the lubricant composition can comprise from about 0.05% to about 3% by weight, for example from about 0.2% to about 1.5%, and as a further example from about 0.3% to about 1% by weight relative to the total weight of the lubricant composition. In an aspect, the additive composition can comprise from about 0.3% to about 18% by weight, for example from about 1.2% to about 8.9%, and as a further example from about 1.8% to about 6% by weight relative to the total weight of the additive composition. However, one of ordinary skill in the art would understand that any amount can be used.

The disclosed additive composition can also comprise a friction modifying compound. The friction modifier for use in the disclosed additive composition can be selected from among many suitable compounds and materials useful for imparting this function in lubricant compositions. The friction modifier can be used as a single type of compound or a mixture of different types of compounds. Non-limiting examples of the friction modifier include a nitrogen-containing compound, an ash-containing compound, and a non-nitrogen-containing compound. In an aspect, the disclosed lubricating compositions can comprise a non-nitrogen-containing compound and a molybdenum-containing compound.

The nitrogen-containing compound can be any compound that comprises a basic nitrogen. In an aspect, the nitrogen-containing compound can be a long chain alkylene amine. Long chain alkylene amine friction modifying compounds include, for example, N-aliphatic hydrocarbyl-substituted trimethylenediamines in which the N-aliphatic hydrocarbyl-substituent is at least one straight chain aliphatic hydrocarbyl group free of acetylenic unsaturation and having in the range of about 14 to about 20 carbon atoms. A non-limiting example of such friction modifier compounds is N-oleyl-trimethylene diamine. Other suitable compounds include N-tallow-trimethylene diamine and N-coco-trimethylene diamine.

One group of friction modifiers includes the N-aliphatic hydrocarbyl-substituted diethanol amines in which the N-aliphatic hydrocarbyl-substituent is at least one straight chain aliphatic hydrocarbyl group free of acetylenic unsaturation and having in the range of about 14 to about 20 carbon atoms.

As used herein, the term “hydrocarbyl substituent” or “hydrocarbyl group” is used in its ordinary sense, which is well-known to those skilled in the art. Specifically, it refers to a group having a carbon atom directly attached to the remainder of the molecule and having predominantly hydrocarbon character. Examples of hydrocarbyl groups include:

(1) hydrocarbon substituents, that is, aliphatic (e.g., alkyl or alkenyl), alicyclic (e.g., cycloalkyl, cycloalkenyl) substituents, and aromatic-, aliphatic-, and alicyclic-substituted aromatic substituents, as well as cyclic substituents wherein the ring is completed through another portion of the molecule (e.g., two substituents together form an alicyclic radical);

(2) substituted hydrocarbon substituents, that is, substituents containing non-hydrocarbon groups which, in the context of this invention, do not alter the predominantly hydrocarbon substituent (e.g., halo (especially chloro and fluoro), hydroxy, alkoxy, mercapto, alkylmercapto, nitro, nitroso, and sulfoxy);

(3) hetero substituents, that is, substituents which, while having a predominantly hydrocarbon character, in the context of this invention, contain other than carbon in a ring or chain otherwise composed of carbon atoms. Heteroatoms include sulfur, oxygen, nitrogen, and encompass substituents as pyridyl, furyl, thienyl and imidazolyl. In general, no more than two, for example no more than one, non-hydrocarbon substituent will be present for every ten carbon atoms in the hydrocarbyl group; typically, there will be no non-hydrocarbon substituents in the hydrocarbyl group.

As discussed above, the friction modifier can comprise a mixture of different compounds, such as a combination of at least one N-aliphatic hydrocarbyl-substituted diethanol amine and at least one N-aliphatic hydrocarbyl-substituted trimethylene diamine in which the N-aliphatic hydrocarbyl-substituent is at least one straight chain aliphatic hydrocarbyl group free of acetylenic unsaturation and having in the range of about 14 to about 20 carbon atoms. Further details concerning this friction modifier combination are set forth in U.S. Pat. Nos. 5,372,735 and 5,441,656, the disclosures of which are hereby incorporated by reference.

The friction modifier can be an ash-containing compound. In an aspect, the ash-containing compound can be a molybdenum-containing compound. The molybdenum-containing compound for use in the lubricating compositions disclosed herein can be sulfur- and/or phosphorus-free. A sulfur- and phosphorus-free molybdenum-containing compound can be prepared by reacting a sulfur and phosphorus-free molybdenum source with an organic compound containing amino and/or alcohol groups. Examples of sulfur- and phosphorus-free molybdenum sources include molybdenum trioxide, ammonium molybdate, sodium molybdate and potassium molybdate. The amino groups can be monoamines, diamines, or polyamines. The alcohol groups can be mono-substituted alcohols, diols or bis-alcohols, or polyalcohols. As an example, the reaction of diamines with fatty oils produces a product containing both amino and alcohol groups that can react with the sulfur- and phosphorus-free molybdenum source.

Examples of sulfur- and phosphorus-free molybdenum-containing compounds appearing in patents and patent applications which are fully incorporated herein by reference include the following: Compounds prepared by reacting certain basic nitrogen compounds with a molybdenum source as defined in U.S. Pat. Nos. 4,259,195 and 4,261,843. Compounds prepared by reacting a hydrocarbyl substituted hydroxy alkylated amine with a molybdenum source as defined in U.S. Pat. No. 4,164,473. Compounds prepared by reacting a phenol aldehyde condensation product, a mono-alkylated alkylene diamine, and a molybdenum source as defined in U.S. Pat. No. 4,266,945. Compounds prepared by reacting a fatty oil, diethanolamine, and a molybdenum source as defined in U.S. Pat. No. 4,889,647. Compounds prepared by reacting a fatty oil or acid with 2-(2-aminoethyl)aminoethanol, and a molybdenum source as defined in U.S. Pat. No. 5,137,647. Compounds prepared by reacting a secondary amine with a molybdenum source as defined in U.S. Pat. No. 4,692,256. Compounds prepared by reacting a diol, diamino, or amino-alcohol compound with a molybdenum source as defined in U.S. Pat. No. 5,412,130. Compounds prepared by reacting a fatty oil, mono-alkylated alkylene diamine, and a molybdenum source as defined in European Patent Application EP 1 136 496 A1. Compounds prepared by reacting a fatty acid, mono-alkylated alkylene diamine, glycerides, and a molybdenum source as defined in European Patent Application EP 1 136 497 A1. Compounds prepared by reacting a fatty oil, diethanolamine, and a molybdenum source as defined in U.S. Pat. No. 4,889,647.

In an aspect, a sulfur-containing, molybdenum-containing compound can also be used in the lubricating compositions disclosed herein. The sulfur-containing, molybdenum-containing compound can be prepared by a variety of methods. One method involves reacting a sulfur- and/or phosphorus-free molybdenum source with an amino group and one or more sulfur sources. Sulfur sources can include for example, but are not limited to, carbon disulfide, hydrogen sulfide, sodium sulfide and elemental sulfur. Alternatively, the sulfur-containing, molybdenum-containing compound can be prepared by reacting a sulfur-containing molybdenum source with an amino group or thiuram group and optionally a second sulfur source. As an example, the reaction of molybdenum trioxide with a secondary amine and carbon disulfide produces molybdenum dithiocarbanates. Alternatively, the reaction of (NH₄)₂Mo₃S₁₃*n(H₂O) where n ranges from about 0 to 2, with a tetralkylthiuram disulfide, produces a trinuclear sulfur-containing molybdenum dithiocarbamate.

Non-limiting examples of sulfur-containing, molybdenum-containing compounds appearing in patents and patent applications include the following: Compounds prepared by reacting molybdenum trioxide with a secondary amine and carbon disulfide as defined in U.S. Pat. Nos. 3,509,051 and 3,356,702. Compounds prepared by reacting a sulfur-free molybdenum source with a secondary amine, carbon disulfide, and an additional sulfur source as defined in U.S. Pat. No. 4,098,705. Compounds prepared by reacting a molybdenum halide with a secondary amine and carbon disulfide as defined in U.S. Pat. No. 4,178,258. Compounds prepared by reacting a molybdenum source with a basic nitrogen compound and a sulfur source as defined in U.S. Pat. Nos. 4,263,152, 4,265,773, 4,272,387, 4,285,822, 4,369,119, 4,395,343. Compounds prepared by reacting ammonium tetrathiomolybdate with a basic nitrogen compound as defined in U.S. Pat. No. 4,283,295. Compounds prepared by reacting an olefin, sulfur, an amine and a molybdenum source as defined in U.S. Pat. No. 4,362,633. Compounds prepared by reacting ammonium tetrathiomolybdate with a basic nitrogen compound and an organic sulfur source as defined in U.S. Pat. No. 4,402,840. Compounds prepared by reacting a phenolic compound, an amine and a molybdenum source with a sulfur source as defined in U.S. Pat. No. 4,466,901. Compounds prepared by reacting a triglyceride, a basic nitrogen compound, a molybdenum source, and a sulfur source as defined in U.S. Pat. No. 4,765,918. Compounds prepared by reacting alkali metal alkylthioxanthate salts with molybdenum halides as defined in U.S. Pat. No. 4,966,719. Compounds prepared by reacting a tetralkylthiuram disulfide with molybdenum hexacarbonyl as defined in U.S. Pat. No. 4,978,464. Compounds prepared by reacting an alkyl dixanthogen with molybdenum hexacarbonyl as defined in U.S. Pat. No. 4,990,271. Compounds prepared by reacting alkali metal alkylxanthate salts with dimolybdenum tetra-acetate as defined in U.S. Pat. No. 4,995,996. Compounds prepared by reacting (NH₄)₂Mo₃S₁₃*₂H₂O with an alkali metal dialkyldithiocarbamate or tetralkyl thiuram disulfide as define in U.S. Pat. No. 6,232,276. Compounds prepared by reacting an ester or acid with a diamine, a molybdenum source and carbon disulfide as defined in U.S. Pat. No. 6,103,674. Compounds prepared by reacting an alkali metal dialkyldithiocarbamate with 3-chloropropionic acid, followed by molybdenum trioxide, as defined in U.S. Pat. No. 6,117,826.

Non-limiting examples of molybdenum-containing compounds include molybdenum carboxylates, molybdenum amides, molybdenum thiophosphates, molybdenum thiocarbamates, molybdenum dithiocarbamates, and so forth.

Additional examples of ash-containing compounds include, but are not limited to, titanium-containing compounds and tungsten-containing compounds.

Another suitable group of friction modifiers include non-nitrogen-containing compounds, such as polyolesters, for example, glycerol monooleate (GMO), glycerol monolaurate (GML), and the like.

The friction modifying compound can be present in the lubricant composition in any desired or effective amount. In an aspect, the lubricant composition can comprise from about 0.05% to about 3% by weight, for example from about 0.2% to about 1.5%, and as a further example from about 0.3% to about 1% by weight relative to the total weight of the lubricating composition. In an aspect, the additive composition can comprise from about 0.3% to about 18% by weight, for example from about 1.2% to about 8.9%, and as a further example from about 1.8% to about 6% by weight relative to the total weight of the lubricating composition. However, one of ordinary skill in the art would understand that any amount can be used.

The dispersant for use in the disclosed additive composition can be selected from any of the ashless dispersants known to those skilled in the art. Suitable ashless dispersants may include ashless dispersants such as succinimide dispersants, Mannich base dispersants, and polymeric polyamine dispersants. Hydrocarbyl-substituted succinic acylating agents can be used to make hydrocarbyl-substituted succinimides. The hydrocarbyl-substituted succinic acylating agents include, but are not limited to, hydrocarbyl-substituted succinic acids, hydrocarbyl-substituted succinic anhydrides, the hydrocarbyl-substituted succinic acid halides (for example, the acid fluorides and acid chlorides), and the esters of the hydrocarbyl-substituted succinic acids and lower alcohols (e.g., those containing up to 7 carbon atoms), that is, hydrocarbyl-substituted compounds which can function as carboxylic acylating agents.

Hydrocarbyl substituted acylating agents can be made by reacting a polyolefin or chlorinated polyolefin of appropriate molecular weight with maleic anhydride. Similar carboxylic reactants can be used to make the acylating agents. Such reactants can include, but are not limited to, maleic acid, fumaric acid, malic acid, tartaric acid, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, mesaconic acid, ethylmaleic anhydride, dimethylmaleic anhydride, ethylmaleic acid, dimethylmaleic acid, hexylmaleic acid, and the like, including the corresponding acid halides and lower aliphatic esters.

The molecular weight of the olefin can vary depending upon the intended use of the substituted succinic anhydrides. Typically, the substituted succinic anhydrides can have a hydrocarbyl group of from about 8-500 carbon atoms. However, substituted succinic anhydrides used to make lubricating oil dispersants can typically have a hydrocarbyl group of about 40-500 carbon atoms. With high molecular weight substituted succinic anhydrides, it is more accurate to refer to number average molecular weight (Mn) since the olefins used to make these substituted succinic anhydrides can include a mixture of different molecular weight components resulting from the polymerization of low molecular weight olefin monomers such as ethylene, propylene and isobutylene.

The mole ratio of maleic anhydride to olefin can vary widely. It can vary, for example, from about 5:1 to about 1:5, or for example, from about 1:1 to about 3:1. With olefins such as polyisobutylene having a number average molecular weight of about 500 to about 7000, or as a further example, about 800 to about 3000 or higher and the ethylene-alpha-olefin copolymers, the maleic anhydride can be used in stoichiometric excess, e.g. 1.1 to 3 moles maleic anhydride per mole of olefin. The unreacted.maleic anhydride can be vaporized from the resultant reaction mixture.

Polyalkenyl succinic anhydrides can be converted to polyalkyl succinic anhydrides by using conventional reducing conditions such as catalytic hydrogenation. For catalytic hydrogenation, a suitable catalyst is palladium on carbon. Likewise, polyalkenyl succinimides can be converted to polyalkyl succinimides using similar reducing conditions.

The polyalkyl or polyalkenyl substituent on the succinic anhydrides employed herein can be generally derived from polyolefins which are polymers or copolymers of mono-olefins, particularly 1-mono-olefins, such as ethylene, propylene and butylene. The mono-olefin employed can have about 2 to about 24 carbon atoms, or as a further example, about 3 to about 12 carbon atoms. Other suitable mono-olefins include propylene, butylene, particularly isobutylene, 1-octene and 1-decene. Polyolefins prepared from such mono-olefins include polypropylene, polybutene, polyisobutene, and the polyalphaolefins produced from 1-octene and 1-decene.

In some aspects, the ashless dispersant can include one or more alkenyl succinimides of an amine having at least one primary amino group capable of forming an imide group. The alkenyl succinimides can be formed by conventional methods such as by heating an alkenyl succinic anhydride, acid, acid-ester, acid halide, or lower alkyl ester with an amine containing at least one primary amino group. The alkenyl succinic anhydride can be made readily by heating a mixture of polyolefin and maleic anhydride to about 180°-220° C. The polyolefin can be a polymer or copolymer of a lower monoolefin such as ethylene, propylene, isobutene and the like, having a number average molecular weight in the range of about 300 to about 3000 as determined by gel permeation chromatography (GPC).

Amines which can be employed in forming the ashless dispersant include any that have at least one primary amino group which can react to form an imide group and at least one additional primary or secondary amino group and/or at least one hydroxyl group. A few representative examples are: N-methyl-propanediamine, N-dodecylpropanediamine, N-aminopropyl-piperazine, ethanolamine, N-ethanol-ethylenediamine, and the like.

Suitable amines can include alkylene polyamines, such as propylene diamine, dipropylene triamine, di-(1,2-butylene)triamine, and tetra-(1,2-propylene)pentamine. A further example includes the ethylene polyamines which can be depicted by the formula H₂N(CH₂CH₂—NH)_(n)H, wherein n can be an integer from about one to about ten. These include: ethylene diamine, diethylene triamine (DETA), triethylene tetramine (TETA), tetraethylene pentamine (TEPA), pentaethylene hexamine (PEHA), and the like, including mixtures thereof in which case n is the average value of the mixture. Such ethylene polyamines have a primary amine group at each end so they can form mono-alkenylsuccinimides and bis-alkenylsuccinimides. Commercially available ethylene polyamine mixtures can contain minor amounts of branched species and cyclic species such as N-aminoethyl piperazine, N,N′-bis(aminoethyl)piperazine, N,N′-bis(piperazinyl)ethane, and like compounds. The commercial mixtures can have approximate overall compositions falling in the range corresponding to diethylene triamine to tetraethylene pentamine. The molar ratio of polyalkenyl succinic anhydride to polyalkylene polyamines can be from about 1:1 to about 3.0:1.

In some aspects, the dispersant can include the products of the reaction of a polyethylene polyamine, e.g. triethylene tetramine or tetraethylene pentamine, with a hydrocarbon substituted carboxylic acid or anhydride made by reaction of a polyolefin, such as polyisobutene, of suitable molecular weight, with an unsaturated polycarboxylic acid or anhydride, e.g., maleic anhydride, maleic acid, fumaric acid, or the like, including mixtures of two or more such substances.

Polyamines that are also suitable in preparing the dispersants described herein include N-arylphenylenediamines, such as N-phenylphenylenediamines, for example, N-phenyl-1,4-phenylenediamine, N-phenyl-1,3-phenylendiamine, and N-phenyl-1,2-phenylenediamine; aminothiazoles such as aminothiazole, aminobenzothiazole, aminobenzothiadiazole and aminoalkylthiazole; aminocarbazoles; aminoindoles; aminopyrroles; amino-indazolinones; aminomercaptotriazoles; aminoperimidines; aminoalkyl imidazoles, such as 1-(2-aminoethyl)imidazol- e, 1-(3-aminopropyl)imidazole; and aminoalkyl morpholines, such as 4-(3-aminopropyl)morpholine. These polyamines are described in more detail in U.S. Pat. Nos. 4,863,623 and 5,075,383, the disclosures of which are hereby incorporated by reference herein.

Additional polyamines useful in forming the hydrocarbyl-substituted succinimides include polyamines having at least one primary or secondary amino group and at least one tertiary amino group in the molecule as taught in U.S. Pat. Nos. 5,634,951 and 5,725,612, the disclosures of which are hereby incorporated by reference herein. Non-limiting examples of suitable polyamines include N,N,N″,N″-tetraalkyldialkylenetriamines (two terminal tertiary amino groups and one central secondary amino group), N,N,N′,N″-tetraalkyltrialkylenetetramines (one terminal tertiary amino group, two internal tertiary amino groups and one terminal primary amino group), N,N,N′,N″,N′″-pentaalkyltrialkylenetetramines (one terminal tertiary amino group, two internal tertiary amino groups and one terminal secondary amino group), tris(dialkylaminoalkyl)aminoalkylmethanes (three terminal tertiary amino groups and one terminal primary amino group), and like compounds, wherein the alkyl groups are the same or different and typically contain no more than about 12 carbon atoms each, and which can contain from about 1 to about 4 carbon atoms each. As a further example, these alkyl groups can be methyl and/or ethyl groups. Polyamine reactants of this type can include dimethylaminopropylamine (DMAPA) and N-methyl piperazine.

Hydroxyamines suitable for herein include compounds, oligomers or polymers containing at least one primary or secondary amine capable of reacting with the hydrocarbyl-substituted succinic acid or anhydride. Examples of hydroxyamines suitable for use herein include aminoethylethanolamine (AEEA), aminopropyidiethanolamine (APDEA), ethanolamine, diethanolamine (DEA), partially propoxylated hexamethylene diamine (for example HMDA-2PO or HMDA-3PO), 3-amino-1,2-propanediol, tris(hydroxymethyl)aminomethane, and 2-amino-1,3-propanediol.

The mole ratio of amine to hydrocarbyl-substituted succinic acid or anhydride can range from about 1:1 to about 3,0:1. Another example of a mole ratio of amine to hydrocarbyl-substituted succinic acid or anhydride may range from about 1.5:1 to about 2.0:1.

The foregoing dispersant can also be a post-treated dispersant made, for example, by treating the dispersant with maleic anhydride and boric acid as described, for example, in U.S. Pat. No. 5,789,353, or by treating the dispersant with nonylphenol, formaldehyde and glycolic acid as described, for example, in U.S. Pat. No. 5,137,980, the disclosures of which are hereby incorporated by reference in their entirety.

The Mannich base dispersants can be a reaction product of an alkyl phenol, typically having a long chain alkyl substituent on the ring, with one or more aliphatic aldehydes containing from about 1 to about 7 carbon atoms (for example, formaldehyde and derivatives thereof), and polyamines (especially polyalkylene polyamines). For example, a Mannich base ashless dispersants can be formed by condensing about one molar proportion of long chain hydrocarbon-substituted phenol with from about 1 to about 2.5 moles of formaldehyde and from about 0.5 to about 2 moles of polyalkylene polyamine.

Hydrocarbon sources for preparation of the Mannich polyamine dispersants can be those derived from substantially saturated petroleum fractions and olefin polymers, such as polymers of mono-olefins having from 2 to about 6 carbon atoms. The hydrocarbon source generally contains, for example, at least about 40 carbon atoms, and as a further example, at least about 50 carbon atoms to provide substantial oil solubility to the dispersant. The olefin polymers having a GPC number average molecular weight range from about 600 to 5,000 can be suitable. However, polymers of higher molecular weight can also be used. Suitable hydrocarbon sources can be isobutylene polymers and polymers made from a mixture of isobutene and a raffinate stream.

Suitable Mannich base dispersants can be Mannich base ashless dispersants formed by condensing about one molar proportion of long chain hydrocarbon-substituted phenol with from about 1 to about 2.5 moles of formaldehyde and from about 0.5 to about 2 moles of polyalkylene polyamine.

Polymeric polyamine dispersants suitable as the ashless dispersants are polymers containing basic amine groups and oil solubilizing groups (for example, pendant alkyl groups having at least about 8 carbon atoms). Such materials are illustrated by interpolymers formed from various monomers such as decyl methacrylate, vinyl decyl ether or relatively high molecular weight olefins, with aminoalkyl acrylates and aminoalkyl acrylamides. Examples of polymeric polyamine dispersants are set forth in U.S. Pat. Nos. 3,329,658; 3,449,250; 3,493,520; 3,519,565; 3,666,730; 3,687,849; and 3,702,300. Polymeric polyamines can include hydrocarbyl polyamines wherein the hydrocarbyl group is composed of the polymerization product of isobutene and a raffinate I stream as described above. PIB-amine and PIB-polyamines may also be used.

Methods for the production of ashless dispersants as described above are known to those skilled in the art and are reported in the patent literature. For example, the synthesis of various ashless dispersants of the foregoing types is described in such patents as U.S. Pat. Nos. 2,459,112; 2,962,442, 2,984,550, 3,036,003; 3,163,603, 3,166,516; 3,172,892; 3,184,474; 3,202,678; 3,215,707; 3,216,936; 3,219,666; 3,236,770; 3,254,025; 3,271,310; 3,272,746; 3,275,554; 3,281,357; 3,306,908; 3,311,558; 3,316,177; 3,331,776; 3,340,281; 3,341,542; 3,346,493; 3,351,552; 3,355,270; 3,368,972; 3,381,022; 3,399,141; 3,413,347; 3,415,750; 3,433,744; 3,438,757; 3,442,808; 3,444,170; 3,448,047; 3,448,048; 3,448,049; 3,451,933; 3,454,497; 3,454,555; 3,454,607; 3,459,661; 3,461,172; 3,467,668; 3,493,520; 3,501,405; 3,522,179; 3,539,633; 3,541,012; 3,542,680; 3,543,678; 3,558,743; 3,565,804; 3,567,637; 3,574,101; 3,576,743; 3,586,629; 3,591,598; 3,600,372; 3,630,904; 3,632,510; 3,632,511; 3,634,515; 3,649,229; 3,697,428; 3,697,574; 3,703,536; 3,704,308; 3,725,277; 3,725,441; 3,725,480; 3,726,882; 3,736,357; 3,751,365; 3,756,953; 3,793,202; 3,798,165; 3,798,247; 3,803,039; 3,804,763; 3,836,471; 3,862,981; 3,872,019; 3,904,595; 3,936,480; 3,948,800; 3,950,341; 3,957,746; 3,957,854; 3,957,855; 3,980,569; 3,985,802; 3,991,098; 4,006,089; 4,011,380; 4,025,451; 4,058,468; 4,071,548; 4,083,699; 4,090,854; 4,173,540; 4,234,435; 4,354,950; 4,485,023; 5,137,980, and Re 26,433, herein incorporated by reference.

An example of a suitable ashless dispersant is a borated dispersant. Borated dispersants can be formed by boronating (“borating”) an ashless dispersant having basic nitrogen and/or at least one hydroxyl group in the molecule, such as a succinimide dispersant, succinamide dispersant, succinic ester dispersant, succinic ester-amide dispersant, Mannich base dispersant, or hydrocarbyl amine or polyamine dispersant. Methods that can be used for borating the various types of ashless dispersants described above are described in U.S. Pat. Nos. 3,087,936; 3,254,025; 3,281,428; 3,282,955; 2,7284,409; 2,284,410; 3,338,832; 3,344,069; 3,533,945; 3,658,836; 3,703,536; 3,718,663; 4,455,243; and 4,652,387, the disclosures of which are hereby incorporated by reference in their entirety.

The borated dispersant can include a high molecular weight dispersant treated with boron such that the borated dispersant includes up to about 2 wt % of boron, for example from about 0.8 wt % or less of boron, as a further example from about 0.1 to about 0.7 wt % of boron, as an even further example, from about 0.25 to about 0.7 wt % of boron, and as a further example from about 0.35 to about 0.7 wt % of boron. The dispersant can be dissolved in oil of suitable viscosity for ease of handling. It should be understood that the weight percentages given here are for neat dispersant, without any diluent oil added.

A dispersant can be further reacted with an organic acid, an anhydride, and/or an aldehyde/phenol mixture. Such a process can enhance compatibility with elastomer seals, for example. The borated dispersant can further include a mixture of borated dispersants. As a further example, the borated dispersant can include a nitrogen-containing dispersant and/or may be free of phosphorus.

In an aspect, the dispersant for use in the disclosed lubricant composition can be an ethylene-propylene dispersant. In particular, the dispersant can be an ethylene-propylene copolymer grafted with maleic anhydride and reacted with n-phenyl phenylene diamine.

Low molecular weight ethylene- alpha-olefin succinic anhydride dispersants, as described in U.S. Pat. Nos. 5,075,383 and 6,117,825, the disclosures of which are hereby incorporated by reference, are also suitable for use herein. Also suitable in the present disclosure are ethylene alpha-olefin polymers as described in U.S. Pat. Nos. 5,266,223; 5,350,532; and 5,435,926, the disclosures of which are hereby incorporated by reference. Ethylene-propylene diene polymers, such as those described in U.S. Pat. Nos. 4,952,637, 5,356,999, 5,374,364, and 5,424,366, the disclosures of which are hereby incorporated by reference, are also suitable.

A cross-linked low molecular weight ethylene-propylene succinic anhydride dispersant is also suitable for use in the present invention. These cross-linked dispersants are similar to the low molecular weight ethylene alpha-olefin succinic anhydride dispersants discussed above, but additionally contain a multifunctional polyamine to achieve advantageous cross linking, as described in U.S. Pat. No. 6,107,258, the disclosure of which is hereby incorporated by reference.

Suitable dispersants will be derived from ethylene-alpha-olefin polymers having a molecular weight of ranging from about 300 to about 25,000, for example from about 1000 to about 15,000; more as a further example from about 5,000 to about 15,000.

In an additional aspect, the dispersant can be a highly grafted, amine derivatized functionalized ethylene-propylene copolymer as described fully in U.S. Pat. Nos. 5,139,688 and 6,107,257, the disclosures of which are hereby incorporated by reference.

In an aspect, the dispersant can be a functionalized olefin copolymer. The polymer or copolymer substrate can be prepared from ethylene and propylene or it can be prepared from ethylene and at least one higher olefin within the range of C₃ to C₂₃ alpha-olefins.

Non-limiting examples of polymers for use herein include copolymers of ethylene and at least one C₃ to C₂₃ alpha-olefins. In an aspect, copolymers of ethylene and propylene can be used. Other alpha-olefins suitable in place of propylene to form the copolymer or to be used in combination with ethylene and propylene to form a terpolymer include 1-butene, 2-butene, isobutene, 1-pentene, 1-hexene, 1-octene and styrene; α,ω-diolefins such as 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, branched chain alpha-olefins such as 4-methylbutene-1,5-methylpentene-1, and 6-methylheptene-1; and mixtures thereof.

More complex polymer substrates, often designated as interpolymers, can be prepared using a third component. The third component generally used to prepare an interpolymer substrate can be a polyene monomer selected from non-conjugated dienes and trienes. The non-conjugated diene component can be one having from 5 to 14 carbon atoms in the chain. For example, the diene monomer can be characterized by the presence of a vinyl group in its structure and can include cyclic and bicyclo compounds. Representative dienes include 1,4-hexadiene, 1,4-cyclohexadiene, dicyclopentadiene, 5-ethylidene-2-norbornene, 5-methylene-2-norborene, 1,5-heptadiene, and 1,6-octadiene. A mixture of more than one diene can be used in the preparation of the interpolymer. In an embodiment, a non-conjugated diene for preparing a terpolymer or interpolymer substrate can be 1,4-hexadiene.

The triene component can have at least two non-conjugated double bonds, and up to about 30 carbon atoms in the chain. Typical trienes useful in preparing the interpolymer of the invention can be 1-isopropylidene-3α,4,7,7α.-tetrahydroindene, 1-isopropylidenedicyclopentadiene, dihydro-isodicyclopentadiene, and 2-(2-methylene-4-methyl-3-pentenyl)(2.2.1)bicyclo-5-heptene.

Ethylene-propylene or higher alpha-olefin copolymers can comprise from about 15 to 80 mole percent ethylene and from about 85 to 20 mole percent C₃ to C₂₃ alpha-olefin with, for example, mole ratios from about 35 to 75 mole percent ethylene and from about 65 to 25 mole percent of a C₃ to C₂₃ alpha-olefin, with for example proportions being from 50 to 70 mole percent ethylene and 50 to 30 mole percent C₃ to C₂₃ alpha-olefin, and as a further example proportions being from 55 to 65 mole percent ethylene and 45 to 35 mole percent C₃ to C₂₃ alpha-olefin.

Terpolymer variations of the foregoing polymers can comprise from about 0.1 to 10 mole percent of a non-conjugated diene or triene.

The terms polymer and copolymer can be used generically to encompass ethylene copolymers, terpolymers or interpolymers. These materials can comprise minor amounts of other olefinic monomers so long as the basic characteristics of the ethylene copolymers are not materially changed. One of ordinary skill in the art would understand how to make these functionalized olefin copolymers. For example, U.S. Pat. No. 6,107,257, the disclosure of which is hereby incorporated by reference, discloses methods for making functionalized olefin copolymers.

The dispersant can also be a polyalkyl (meth)acrylate copolymer comprising units derived from: (A) about 12 to about 18 weight percent methyl methacrylate; (B) about 75 to about 85 weight percent of C₁₀ -C₁₅ alkyl (meth)acrylate(s); and (C) about 2 to about 5 weight percent of a nitrogen-containing dispersant monomer. The polyalkyl (meth)acrylate copolymers can comprise the reaction products of: (A) from about 12 to about 18, weight percent methyl methacrylate; (B) from about 75 to about 85, weight percent of C₁₀-C₁₅ alkyl (meth)acrylate(s); and (C) from about 2 to about 5, weight percent of a nitrogen-containing dispersant monomer.

As used herein C₁₀-C₁₅ alkyl (meth)acrylate means an alkyl ester of acrylic or methacrylic acid having a straight or branched alkyl group of 10 to 15 carbon atoms per group including, but not limited to, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, lauryl (meth)acrylate, myristyl (meth)acrylate, dodecyl pentadecyl methacrylate, and mixtures thereof.

The alkyl (meth)acrylate comonomers containing 10 or more carbon atoms in the alkyl group can generally be prepared by standard esterification procedures using technical grades of long chain aliphatic alcohols, and these commercially available alcohols are mixtures of alcohols of varying chain lengths in the alkyl groups. Consequently, for the purposes of this disclosure, alkyl (meth)acrylate is intended to include not only the individual alkyl (meth)acrylate product named, but also to include mixtures of the alkyl (meth)acrylates with a predominant amount of the particular alkyl (meth)acrylate named.

The nitrogen-containing dispersant monomers suitable for use herein include dialkylamino alkyl (meth)acrylamides such as, N,N-dimethylaminopropyl methacrylamide, N,N-diethylaminopropyl methacrylamide; N,N-dimethylaminoethyl acrylamide and N,N-diethylaminoethyl acrylamide; and dialkylaminoalkyl (meth)acrylates such as N,N-dimethylaminoethyl methacrylate; N,N-diethylaminoethyl acrylate and N,N-dimethylaminoethyl thiomethacrylate.

In an aspect, the polyalkyl (meth)acrylate copolymers consist essentially of the reaction products of (A), (B) and (C). However, those skilled in the art will appreciate that minor levels of other monomers, polymerizable with monomers (A), (B) and/or (C) disclosed herein, can be present as long as they do not adversely affect the low temperature properties of the fully formulated fluids. Typically additional monomers are present in an amount of less than about 5 weight percent, for example in an amount of less than 3 weight percent, and as a further example in an amount of less than 1 weight percent. For example, the addition of minor levels of monomers such as C₂-C₉ alkyl (meth)acrylates, hydroxy- or alkoxy-containing alkyl (meth)acrylates, ethylene, propylene, styrene, vinyl acetate and the like are contemplated within the scope of this disclosure. In an aspect, the sum of the weight percent of (A), (B) and (C) equals 100%.

The copolymers can be prepared by various polymerization techniques including free-radical and anionic polymerization.

Conventional methods of free-radical polymerization can be used to prepare the copolymers. Polymerization of the acrylic and/or methacrylic monomers can take place under a variety of conditions, including bulk polymerization, solution polymerization, usually in an organic solvent, preferably mineral oil, emulsion polymerization, suspension polymerization and non-aqueous dispersion techniques.

The dispersant can be present in the lubricant composition in any desired or effective amount. In an aspect, the lubricant composition can comprise from about 0.1% to about 10% by weight, for example from about 1% to about 7%, and as a further example from about 2% to about 5% by weight relative to the total weight of the lubricating composition. In an aspect, the additive composition can comprise from about 0.6% to about 59.5% by weight, for example from about 5.95% to about 41.7%, and as a further example from about 11.9% to about 29.8% by weight relative to the total weight of the additive composition.

According to various embodiments, there is a lubricant composition comprising a major amount of a base oil and a minor amount of the additive composition comprising a friction modifier and a dispersant, wherein the additive composition exhibits at least one of reduced thin-film friction and increased fuel efficiency as compared to an additive composition that is devoid of the friction modifier and the dispersant.

Optionally, other components can be present in the disclosed lubricant and/or additive compositions. Non-limiting examples of other components include antiwear agents, detergent, diluents, defoamers, demulsifiers, anti-foam agents, corrosion inhibitors, extreme pressure agents, seal well agents, antioxidants, pour point depressants, rust inhibitors, and friction modifiers.

In an aspect, an engine, a transmission or a gear set can be lubricated with the disclosed lubricant compositions. However, one of ordinary skill in the art would understand that the disclosed lubricant compositions can be used to lubricate anything, e.g., any surface, such as those where thin-film friction can be present. In another aspect, there is a method for lubricating a machine such as an engine, transmission, automotive gear, a gear set, and/or an axle comprising providing to the machine the disclosed lubricant compositions.

According to various aspects, there is a method of reducing thin-film friction of a fluid between surfaces comprising providing to the fluid a lubricant composition comprising a base oil and an additive composition comprising a detergent and an additive chosen from a phosphorus-containing compound, a friction modifier, and a dispersant.

According to yet another aspect, there is a method of reducing thin-film friction of a fluid between surfaces comprising providing to the fluid a lubricant composition comprising a base oil and an additive composition comprising a friction modifier and a dispersant.

In various aspects, there is a method of increasing fuel efficiency in a vehicle comprising providing to a vehicle a composition comprising a base oil and an additive composition comprising a detergent and an additive chosen from a phosphorus-containing compound, a friction modifier, and a dispersant.

Others aspects disclose a method of increasing fuel efficiency in a vehicle comprising providing to a vehicle a composition comprising a base oil and an additive composition comprising a friction modifier and a dispersant.

Also disclosed herein is a method of lubricating a machine, such as an engine, transmission, automotive gear, a gear set, and/or an axle with the disclosed lubricant compositions. In a further aspect, there is disclosed a method of improving fuel efficiency in a machine, such as an engine, a transmission, an automotive gear, a gear set, and/or an axle comprising placing the disclosed lubricant compositions in the machine, such as an engine, a transmission, an automotive gear, a gear set, and/or an axle.

It is further envisioned that the disclosed lubricant compositions can be provided to any machinery wherein fuel economy is an issue.

EXAMPLE 1 Effect of Individual Additives on Thin Film Friction

The effect of individual additives, such as detergent, phosphorus-containing compound (P-A (metal-containing, phosphorus-containing) and P—B (non-metal-containing, phosphorus-containing)), friction modifier (FM-A (nitrogen-containing), FM-B (non-nitrogen-containing), and FM-C (non-nitrogen-containing)), and a dispersant (D-A (succinimide) and D-B (polymer)), on thin-film friction when added to two base oils, group II base oil (G2) and group IV base oil (PAO4) is shown in Table 1. The thin-film friction was measured at 100° C./20N load with a 20% slide to roll ratio at 1.5 m/s. Table 1 also shows the % change in thin-film friction versus base oil. As can be seen all additives except D-A in G2 caused thin-film friction to increase. However, D-A can cause thin-film friction to increase when added to PAO4.

TABLE 1 Thin-Film % Change in Friction Thin-film friction Coefficient versus base oil G2 0.030 — G2 + DETERGENT 0.069 130% G2 + P-A 0.074 147% G2 + P-B 0.050 68% G2 + FM-A 0.038 27% G2 + FM-B 0.035 17% G2 + D-A 0.029 −3% G2 + D-B 0.056 87% PAO4 0.027 — PAO4 + D-A 0.041 52% PAO4 + FM-A 0.035 30% PAO4 + FM-C 0.036 33%

EXAMPLE 2 Effect of Additive Composition on Thin-Film Friction of the Base Oil G2

Table 2 shows the effect of an additive composition comprising a detergent and an additive chosen from a phosphorus-containing compound (P-A and P—B), a friction modifier (FM-A, FM-B, and FM-C), and a dispersant (D-A and D-B) in a base oil G2 on thin-film friction. The actual and calculated percent changes in thin-film friction are also listed in Table 2. When additives are combined in a base oil, a calculated percent change in thin-film friction of the base oil can be determined by adding the percent change in thin-film friction of the base oil for each individual additive as listed in Table 1. For example the calculated percent change in thin-film friction for the combination of Detergent and P-A in the base oil RLOP 100 would be 277% (130%+147%). Table 2 shows these calculated percent changes in thin-film friction determined from the effect of individual additives. If the actual percent change in thin-film friction for the combination of additives is less than the calculated percent change in thin-film friction, then the thin-film friction measured is unexpectedly low and the combination of additives would have better fuel economy properties than would be expected.

TABLE 2 % Change in % Change in Thin-film Thin-film Thin-Film friction versus friction versus Friction base oil base oil Coefficient ACTUAL CALCULATED G2 + DETERGENT + 0.083 177% 277% P-A G2 + DETERGENT + 0.053 77% 198% P-B G2 + DETERGENT + 0.048 60% 157% FM-A G2 + DETERGENT + 0.059 97% 147% FM-B G2 + DETERGENT + 0.036 20% 127% D-A G2 + DETERGENT + 0.049 63% 217% D-A

In all cases listed in Table 2, the additive composition comprising a detergent (Detergent) and an additive chosen from a phosphorus-containing compound (P-A and P—B), a friction modifier (FM-A and FM-B), and a dispersant (D-A) in the base oil G2 had a lower actual percent change in thin-film friction than a calculated percent change in thin-film friction. Therefore, the additive composition comprising a detergent and an additive chosen from a phosphorus-containing compound, a friction modifier, and a dispersant in the base oil had unexpectedly better thin-film friction and thus fuel efficiency than expected.

EXAMPLE 3 Effect of Additive Composition on Thin Film Friction of the Base Oil PAO4

Table 3 shows the effect of an additive composition comprising a friction modifier (FM-A and FM-C) and a dispersant (D-A) in a base oil PAO4 on thin-film friction. The actual and calculated percent change in thin-film friction are also listed in Table 3. In all cases listed in Table 3, the additive composition comprising a friction modifier (FM-A and FM-C) and a dispersant (D-A) in a base oil PAO4 had a lower actual percent change in thin-film friction than calculated from the effect of the individual additives.

TABLE 3 % Change in % Change in Thin-film Thin-film Thin-Film friction versus friction versus Friction base oil base oil Coefficient ACTUAL CALCULATED PAO4 + D-A + FM-A 0.016 −42% 81% PAO4 + D-A + FM-C 0.013 −53% 85%

At numerous places throughout this specification, reference has been made to a number of U.S. patents, published foreign patent applications and published technical papers. All such cited documents are expressly incorporated in full into this disclosure as if fully set forth herein.

For the purposes of this specification and appended claims, unless otherwise indicated, all numbers expressing quantities, percentages or proportions, and other numerical values used in the specification and claims, are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Moreover, all ranges disclosed herein are to be understood to encompass any and all sub-ranges subsumed therein. For example, a range of “less than 10” can include any and all sub-ranges between (and including) the minimum value of zero and the maximum value of 10, that is, any and all sub-ranges having a minimum value of equal to or greater than zero and a maximum value of equal to or less than 10, e.g., 1 to 5.

It is noted that, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the,” include plural referents unless expressly and unequivocally limited to one referent. Thus, for example, reference to “an antioxidant” includes one or more different antioxidants. As used herein, the term “include” and its grammatical variants are intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that can be substituted or added to the listed items.

This invention is susceptible to considerable variation in its practice. Therefore the foregoing description is not intended to limit, and should not be construed as limiting, the invention to the particular exemplifications presented hereinabove. Rather, what is intended to be covered is as set forth in the ensuing claims and the equivalents thereof permitted as a matter of law,

Applicant does not intend to dedicate any disclosed embodiments to the public, and to the extent any disclosed modifications or alterations may not literally fall within the scope of the claims, they are considered to be part of the invention under the doctrine of equivalents. 

1. An additive composition comprising: a detergent; and an additive chosen from a phosphorus-containing compound, a friction modifier, and a dispersant; wherein the additive composition exhibits at least one of reduced thin-film friction and increased fuel efficiency as compared to an additive composition that is devoid of the detergent and the additive.
 2. The additive composition of claim 1, wherein the phosphorus-containing compound is a metal-containing, phosphorus-containing compound.
 3. The additive composition of claim 2, wherein the metal-containing, phosphorus-containing compound is a metal dihydrocarbyl dithiophosphate.
 4. The additive composition of claim 3, wherein the metal dihydrocarbyl dithiophosphate is zinc dialkyl dithiophosphate.
 5. The additive composition of claim 1, wherein the phosphorus-containing compound is a sulfur-containing, phosphorus-containing compound.
 6. The additive composition of claim 5, wherein the sulfur-containing, phosphorus-containing compound is chosen from thiophosphates, dithiophosphates, sulfur-containing neopentyl glycol phosphite, and a salt of a sulfur-containing neopentyl glycol phosphite.
 7. The additive composition of claim 1, wherein the friction modifier is at least one of a non-nitrogen-containing compound, a nitrogen-containing compound, and an ash-containing compound.
 8. The additive composition of claim 7, wherein the non-nitrogen-containing compound is a polyolester.
 9. The additive composition of claim 8, wherein the polyolester is chosen from glycerol monooleate and glycerol monolaurate.
 10. The additive composition of claim 7, wherein the nitrogen-containing compound is a long chain alkylene amine.
 11. The additive composition of claim 10, wherein the long chain alkylene amine is chosen from N-oleyl-trimethylene diamine, N-tallow-trimethylene diamine, coco-trimethylene diamine, and mixtures thereof.
 12. The additive composition of claim 7, wherein the nitrogen-containing compound is diethanolamine.
 13. The additive composition of claim 7, wherein the ash-containing compound is a molybdenum-containing compound comprising sulfur.
 14. The additive composition of claim 11, wherein the molybdenum-containing compound is chosen from molybdenum carboxylates, molybdenum amides, molybdenum thiophosphates, molybdenum thiocarbamates, and mixtures thereof.
 15. The additive composition of claim 1, wherein the dispersant is at least one of succinimide, borated succinimide, Mannich dispersant, functionalized olefin copolymer, and poly(meth)acrylate copolymers.
 16. The additive composition of claim 15, wherein the dispersant is a highly grafted, amine derivatized functionalized ethylene-propylene copolymer.
 17. A lubricant composition comprising: a major amount of a base oil; and a minor amount of the additive composition of claim
 1. 18. An engine, a transmission or a gear set lubricated with the lubricant composition according to claim
 17. 19. A method for lubricating a machine comprising providing to the machine the lubricant composition of claim
 17. 20. The method of claim 19, wherein the machine is a gear.
 21. The method of claim 19, wherein the machine is an engine.
 22. An additive composition comprising: a friction modifier; and a dispersant; wherein the additive composition exhibits at least one of reduced thin-film friction and increased fuel efficiency as compared to an additive composition that is devoid of a friction modifier and a dispersant.
 23. The additive composition of claim 22, wherein the friction modifier is at least one of a non-nitrogen-containing compound, a nitrogen-containing compound, and an ash-containing compound.
 24. The additive composition of claim 22, wherein the dispersant is at least one of succinimide, borated succinimide, Mannich dispersant, functionalized olefin copolymer, and poly(meth)acrylate copolymers.
 25. A lubricant composition comprising: a major amount of a base oil; and a minor amount of the additive composition of claim
 22. 26. An engine, a transmission or a gear set lubricated with the lubricant composition according to claim
 25. 27. A method for lubricating a machine comprising providing to the machine the lubricant composition of claim
 25. 28. The method of claim 27, wherein the machine is a gear.
 29. The method of claim 27, wherein the machine is an engine.
 30. A method of reducing thin-film friction of a fluid between surfaces comprising: providing to the fluid a lubricant composition comprising: a base oil; and an additive composition comprising: a detergent; and an additive chosen from a phosphorus-containing compound, a friction modifier, and a dispersant.
 31. A method of reducing thin-film friction of a fluid between surfaces comprising: providing to the fluid a lubricant composition comprising: a base oil; and an additive composition comprising a friction modifier and a dispersant.
 32. A method of increasing fuel efficiency in a vehicle comprising: providing to a vehicle a composition comprising: a base oil; and an additive composition comprising a detergent and an additive chosen from a phosphorus-containing compound, a friction modifier, and a dispersant.
 33. A method of increasing fuel efficiency in a vehicle comprising: providing to a vehicle a composition comprising: a base oil; and an additive composition comprising a friction modifier and a dispersant. 